As various mobile electronic devices including a mobile phone, a PDA or a notebook computer are being developed, demands for light, thin, short and small flat panel display devices that can be applied to the mobile electronic devices are increasing. As a result, research for flat panel display devices such as an LCD (Liquid Crystal Display), PDP (Plasma Display Panel), an FED (Field Emission Display), a VFD (Vacuum Fluorescent Display) is actively ongoing. Of these displays, the LCD is the most prevalent because of its implementation in mass-production techniques, ease of a driving unit, and high picture quality.
The LCD device comprises an array substrate that unit pixels are arranged in a matrix form, a color filter substrate facing the array substrate for displaying colors in natural colors, and a liquid crystal layer contained between the two substrates.
The array substrate and the color filter substrate are bonded to each other by a sealant at edges thereof, and a cell gap is formed therebetween. The cell gap between the array substrate and the color filter substrate is maintained by a spacer.
The spacer serves to maintain a cell gap between an upper substrate and a lower substrate of an LCD panel, and may be divided into a ball spacer and a column spacer (or a pattern spacer) according to a spacer forming method.
The ball spacer is formed on the upper substrate or the lower substrate by a dispensing minute ball shapes along the substrate. The column spacer, on the other hand, is formed by exposing and developing of a photosensitive layer.
A method of forming the ball spacer includes a wet dispensing method, in which the spacer is mixed with alcohol, etc. and then dispensed, or a dry dispensing method for dispensing only the spacer. The dry dispensing method includes an electrostatic dispensing method using static electricity, or an electrostatic discharge dispensing method using an injection pressure of gas. Generally, the electrostatic discharge dispensing method is mainly applied to the LCD panel susceptible to static electricity.
A spacer is formed easily by the dispensing method of ball spacer. However, the dispensing method has disadvantages that a spacer is not formed at a desired position and a forming density of a spacer is not uniform.
By the dispensing method, a spacer may be formed in a unit pixel portion thus to decrease an aperture ratio, or dispensed spacers may be lumped to each other thus to cause problems with the screen.
On the other hand, the column spacer is formed by a photo mask process. Accordingly, a forming position of the column spacer may be freely controlled, and a density and a shape of the spacer may be freely controlled. However, due to the photo process, an amount of a photosensitive material coated on a substrate to form a spacer is wasted thus increasing production cost and environment pollution. Also, an expensive mask is used and several additional processes have to be performed for the photo process.